Bulk measurement of membrane permeability for random cyclic peptides in living cells to guide drug development.

Cyclic peptides are attractive for drug discovery due to their excellent binding properties and the potential to cross cell membranes. However, by far not all cyclic peptides are cell permeable, and measuring or predicting their membrane permeability is not trivial. In this work, we assessed the membrane permeability of thioether-cyclized peptides, a widely used format in drug discovery.